diff --git a/pymisp/api.py b/pymisp/api.py
index 80e5836..1c301e8 100644
--- a/pymisp/api.py
+++ b/pymisp/api.py
@@ -600,7 +600,7 @@ class PyMISP:
                 and new_attribute['errors'][1]['message'] == 'You do not have permission to do that.'):
             # At this point, we assume the user tried to add an attribute on an event they don't own
             # Re-try with a proposal
-            if isinstance(attribute, MISPAttribute):
+            if isinstance(attribute, (MISPAttribute, dict)):
                 return self.add_attribute_proposal(event_id, attribute, pythonify)
         if not (self.global_pythonify or pythonify) or 'errors' in new_attribute:
             return new_attribute
diff --git a/tests/testlive_comprehensive.py b/tests/testlive_comprehensive.py
index 039802d..72cdb2e 100644
--- a/tests/testlive_comprehensive.py
+++ b/tests/testlive_comprehensive.py
@@ -1740,7 +1740,7 @@ class TestComprehensive(unittest.TestCase):
             self.assertTrue(isinstance(attribute, MISPShadowAttribute), attribute)
             # Test if add proposal without category works - https://github.com/MISP/MISP/issues/4868
             attribute = self.user_misp_connector.add_attribute(second.id, {'type': 'ip-dst', 'value': '123.43.32.22'})
-            self.assertTrue(isinstance(attribute, MISPShadowAttribute))
+            self.assertTrue(isinstance(attribute, MISPShadowAttribute), attribute)
             # Add attribute with the same value as an existing proposal
             prop_attr.uuid = str(uuid4())
             attribute = self.admin_misp_connector.add_attribute(second, prop_attr, pythonify=True)